An 1875 Greek lesson book made its way from Bryn Mawr College to Newscripts with a mystery in tow. Could its dark green cloth cover be poisonous?
Poisonous green pigments used to color emerald green Victorian-era dresses sickened manufacturers and wearers in the 19th century. Melissa Tedone, a conservator at Winterthur Museum and Library, wondered if the pigment could also have been used in some of the brightly colored, clothbound books of the period in its collection. A rainbow sampling of texts revealed arsenic signatures in a handful of the green cloth books the team tested. “Ninety-five percent of the green books that did not contain arsenic did contain chromium and lead,” Tedone says. Those compounds most likely came from another pigment known as chrome green, which is a mixture of Prussian blue (Fe4[Fe(CN)6]3) and chrome yellow (PbCrO4). Experimentation revealed that emerald green pigments were bound only loosely to the book cloths and frequently came off the book during handling (J. Am. Inst. Conserv. 2022, DOI: 10.1080/01971360.2022.2031457).
Eager to know if the lesson book was deadly or just deadly dull, this Newscriptster made her way to Delaware, where she met up with Winterthur laboratory head Rosie Grayburn. A side-by-side comparison of sample books presented compelling visual evidence. Our mystery book was much duller than the arsenical books.
“Most of the books are coated in a chrome green slurry to make this green,” Grayburn said, gesturing to the mystery book and a chrome green example from the Winterthur collection. The colors nearly matched. Was the mystery solved? Not quite yet. Qualitative analysis satisfied, we moved into the nitty-gritty. Grayburn showed an X-ray fluorescence spectrum generated from Newscripts’ mysterious lesson book. “We have quite a lot of lead,” she noted. “We also have chromium” and iron. “With this information we can only infer that possibly chrome green is present. We need to use another technique in order to confirm that.” A Raman scan of the book cloth matched best a Prussian blue reference, with one peak matching a chrome yellow reference. The inconsistency is to be expected. “It could be that when I was performing this, I wasn’t looking much at a chrome yellow pigment particle,” Grayburn said. “I was mostly looking at Prussian blue.”
While lead and chromium both ring alarm bells, the difference between chrome green—like the dye on our lesson book—and arsenical green is that the pigments of the former are tightly bound to the book’s cloth, Grayburn said. That means there’s little risk of the pigment’s coming off, so much of our precautions could be dropped.
If you have a potentially poisonous book in your collection, there’s no need to panic. Wear nitrile gloves, place it in a polyethylene bag, and label it. Wash your hands thoroughly before and after handling the book. Then sign up for the next round of identification bookmarks from Winterthur, and use the color swatches to see if your book warrants extra care.
A question from reader Ryan Smith got us thinking. What exactly is C&EN made of? Well, besides hours of research and a soupçon of inspiration, the recipe for C&EN’s print magazine is relatively simple.
We send off our pages, sometimes 40 or more,
and they arrive at our printer where they stay henceforth.
The printer lasers a plate to print out each page
full of chemistry news to keep you engaged.
The paper it’s printed on is called a coated number five,
a sturdy medium to keep our stories alive.
The coating allows us to use slightly less ink,
which sounds like a good deal, don’t you think?
We understand the concerns about waxy coatings, but our printer reassures us,
they don’t use BPA or the forever chemicals, PFAS.
Dots of ink make the images, graphics, and text.
All composites of magenta, cyan, yellow, and black.
Carbon black helps us cast our textual spell.
For magenta, cyan, and yellow, organic pigments do well.
For every print order, we use
9,500 feet of wire and 7,225 sheets of coated paper.
That’s a whole lot of material, but never you fear!
You can recycle your issues if you don’t want them near.
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